1. Field of the Invention
This invention relates in general to devices for non-invasively measuring blood flow in the human body, and in particular to a garment to be worn for applying electrodes to a body for impedance plethysmograph measurements.
2. Description of the Prior Art
Impedance plethysmographs are known in the art. The plethysmograph measurement non-invasively determines blood pulse volume and blood flow in a segment of the body. Four electrodes are placed on the skin adjacent the particular portion of the body to be measured. The outer pair of the electrodes introduces constant current, while the inner pair detects the variations in the voltage. Instruments used for impedance plethysmograph are described in U.S. Pat. Nos. 3,340,867 and 3,835,840.
Generally the electrodes are conductive metal rings. One difficulty associated with making the plethysmograph measurements is that the rings must fit tightly against the skin. Because limb and body size varies considerably, a large variety of rings are required. Also a conductive ointment at the interface is normally needed to provide better contact and reduce noise.
A tightly fitting vest, having electrodes attached, is described in U.S. Pat. No. 3,534,727. The vest is designed for use in vector-cardiology measurements while physically exercising, and has several large electrodes spaced around the upper region of the user's body. The electrodes are comprised of conductive fabric stretched over layers of padding and semirigid material to provide a contour to fit the body. The electrodes are detachably attached to the inside of a nylon vest and wired together. Repositioning of the electrodes are necessary for different body sizes. Such a vest lacks the necessary spacing of electrodes and is unnecessarily complex for impedance plethysmograph measurements.